Optical information recording medium and optical information recording and reproducing apparatus

ABSTRACT

An optical information recording and reproducing apparatus for recording and reproducing an information signal on/from both concave portions and convex portions of guide grooves formed on a recording medium is disclosed. The optical information recording and reproducing apparatus includes: an optical portion for focusing a light beam emitted from a light source on the recording medium; a focusing control portion for controlling a focal point of the light beam; a tracking control portion for controlling the position of the light beam; a selection portion for selecting which of the concave portions and the convex portions of the guide grooves are used for recording or reproducing; a polarity inverting portion for inverting the polarity of an output signal from the tracking control portion depending on a result selected by the selection portion; a waveform setting portion for setting a modulation pattern for the light; and a signal reproduction portion for demodulating the information signal from a light reflected or transmitted by recorded marks recorded on the recording medium; wherein at least one of the focusing control portion, the tracking control portion, the waveform setting portion and the signal reproduction portion has at least two kinds of operation conditions for recording and reproducing the information signal on/from the concave portions and the convex portions of the guide grooves, and wherein the operation conditions are selected depending on the result selected by the selection portion.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an optical information recording mediumand an optical information recording and reproducing apparatus forrecording and reproducing information by using a light beam. Moreparticularly, the present invention relates to an optical informationrecording medium and an optical information recording and reproducingapparatus allowing for obtaining a higher track density by recording asignal on both lands and grooves of the guide grooves thereof.

2. Description of the Related Art

Optical disks, optical cards, optical tapes and the like are well-knownas recording mediums (or recording members) for recording and/orreproducing information by the use of an optical means. In order torecord information on such a recording medium, a laser beam is generallyused as a light source. More specifically, information is recorded byprecisely focusing a light beam through a lens so as to irradiate thelight beam on a recording thin film of the recording medium.

An optical disk, one of the above-cited recording media, includes acircular substrate on which spiral or concentric guide grooves having aplurality of convex portions and concave portions are provided, and arecording thin film formed thereon. By irradiating a light beam, whichis intensity-modulated in accordance with each information signal, alongthe direction of these guide grooves, information is recorded on therecording thin film.

The recording thin film is required to exhibit such characteristics thatthe physical properties thereof are varied upon the irradiation oflight, and that the difference between the states before and after thevariation may be optically detected. The variations in the physicalproperties of the recording thin film, are for example, the deformationof the thin film owing to the absorption of the light, the phase changeof the thin film owing to the light irradiation, and the like. Therecording media showing such variations are known as a deformation typerecording medium and phase-change type recording medium, respectively. Asignal indicating the variations of the physical, properties asdifference in the amounts of the reflected light is reproduced.

A magnetooptic recording medium is also well-known as another opticaltype recording medium. In a magnetooptic recording medium, informationis recorded thereon by the application of a magnetic field as well aslight irradiation, and the difference in the magnetization directions onthe recording thin film is detected by utilizing a Kerr effect, therebyreproducing a signal.

Optical type recording media such as those described above have been putinto practical use depending on the respective applications thereof. Inaddition, in order to further increase the memory capacity forinformation, various kinds of researches on the increase of therecording density have been earnestly conducted.

As an exemplary method for increasing the recording density of anoptical type recording medium, a method for recording a signal both onthe convex portions and concave portions of the guide grooves isproposed so as to replace a conventional method for recording a signalon either the convex portions or the concave portions of the guidegrooves (e.g., Japanese Journal of Applied Physics, Vol. 32 (1993), pp.5324-5328). According to the method disclosed therein, by using asubstrate in which the width of a concave portion of each guide grooveis approximately equal to that of a convex portion thereof, and thedepth of the concave portion is optimized, an information signal may berecorded and reproduced on/from both of the concave portion and theconvex portion. In this specification, a convex portion with respect tothe light incident direction is called a “groove”, and the operation ofrecording information on a convex portion is called a “grooverecording”. In the same way, a concave portion with respect to the lightincident direction is called a “land”, and the operation of recordinginformation on a concave portion is called a “land recording”. If amethod for recording a signal on both of lands and grooves is employed,a track density is considered to become double as compared with aconventional method in which information is recorded on either one sideof each guide groove.

In recording and reproducing information in accordance with this method,the same kinds of optical systems and optical type recording systems asconventional ones may be used in principle. This method may be realizedeasily by additionally providing a tracking polarity switching means soas to correspond to each concave portion and each convex portion of theguide grooves, and by irradiating an intensity-modulated light beam onthe two kinds of regions based on the information signals. However, thecomparison of the two kinds of signals recorded on the two kinds ofportions of the recording medium reveals that difference exists in theamplitude and the frequency characteristics of the two kinds ofreproduced signals corresponding to a land and a groove, respectively.Such difference in the amplitude of the signals is also caused dependingon the configuration of the respective recording thin films. Therefore,even if a signal recording may be satisfactorily performed on either oneof a land track and a groove track during a step of demodulating areproduced signal, a great deal of error is generated on the other kindof track in some cases. Also, even in recording thin films having thesame configuration, if the shape of the edges of the guide grooves orthe groove width become different from each other, the levels of thereproduced signals become different on the two kinds of tracks.

Accordingly, in a conventional recording medium for performing aland/groove recording, there exists problems to be solved in that theconfiguration of a recording thin film is required to be optimized andthat the guide grooves on the substrate must be shaped with highprecision.

SUMMARY OF THE INVENTION

An optical information recording and reproducing apparatus for recordingand reproducing an information signal on/from both concave portions andconvex portions of guide grooves formed on a recording medium isprovided. The recording medium has: a substrate on which the guidegrooves consisting of the concave portions and the convex portions areformed; and a recording thin film, formed on the guide grooves, on whichvariations to be detected optically are generated by irradiation oflight is provided. The optical information recording and reproducingapparatus of the invention includes: an optical portion, having a lightsource, for focusing a light beam emitted from the light source on therecording medium using an objective lens; a focusing control portion forcontrolling so as to make a focal point of the light beam correspond toa position of the recording thin film; a tracking control portion forcontrolling a position of the light beam in a direction substantiallyvertical to the guide grooves so that the light beam tracks the guidegrooves; a selection portion for selecting which of the concave portionsand the convex portions of the guide grooves are used for recording ainformation signal thereon or reproducing a recorded information signaltherefrom; a polarity inverting portion for inverting the polarity of anoutput signal from the tracking control portion depending on a resultselected by the selection portion; a waveform setting portion forsetting a modulation pattern for the light beam to be irradiated on therecording medium in accordance with the information signal; and a signalreproduction portion for demodulating the information signal from alight reflected or transmitted by recorded marks recorded on therecording medium; wherein at least one of the focusing control portion,the tracking control portion, the waveform setting portion and thesignal reproduction portion has at least two kinds of operationconditions for recording and reproducing the information signal on/fromthe concave portions and the convex portions of the guide grooves, andwherein the operation conditions are selected depending on the resultselected by the selection portion.

According to another aspect of the invention, an optical informationrecording and reproducing apparatus includes: an optical portion, havinga light source, for focusing a light beam emitted from the light sourceon the recording medium using an objective lens; a focusing controlportion for controlling so as to make a focal point of the light beamcorrespond to a position of the recording thin film; a tracking controlportion for controlling the position of the light beam in a directionsubstantially vertical to the guide grooves so that the light beamtracks the guide grooves; a selection portion for selecting which of theconcave portions and the convex portions of the guide grooves are usedfor recording the information signal thereon or reproducing a recordedinformation signal therefrom; a polarity inverting portion for invertingthe polarity of an output signal from the tracking control portiondepending on a result selected by the selection portion; and an opticalmodulation portion including a waveform setting portion having at leasttwo kinds of modulation patterns in accordance with the informationsignal in order to record the information signal on each of the concaveportions and the convex portions of the guide grooves so as to outputany of the modulation patterns depending on the result selected by theselection portion, wherein the optical modulation portion modulates anintensity of the light beam in accordance with the modulation patternsoutput from the waveform setting portion.

In one embodiment of the invention, the waveform setting portion has amultiple pulse modulation function for irradiating a light consisting ofa plurality of pulse sequences onto one recorded mark to be recorded onthe recording medium, and wherein waveforms of the plurality of pulsesequences are different from each other among the at least two kinds ofmodulation patterns of the waveform setting portion.

In one embodiment of the invention, the said at least two kinds ofmodulation patterns of the waveform setting portion vary the power ofthe light beam.

In one embodiment of the invention, the recording and reproducingapparatus further includes a signal reproduction portion fordemodulating the information signal from a light reflected ortransmitted by recorded marks recorded on the recording medium, whereinbefore recording the information signal on the recording medium, thewaveform setting portion includes a recording condition setting portionin which a plurality of pulse patterns are stored in order to irradiatethe light beam having different modulation patterns onto the concaveportions and/or the convex portions of the guide grooves in a test zoneclose to an information zone on the recording medium; and wherein aplurality of recorded marks are formed on the recording medium byirradiating the light beam modulated by the optical modulation portionin accordance with the plurality of pulse patterns, information signalsto be obtained from the plurality of recorded marks formed on therecording medium are demodulated by the signal reproduction portion, andqualities of a plurality of reproduced signals obtained by the signalreproduction portion are compared with each other, thereby determiningrecording conditions optimized for the concave portions and the convexportions of the guide grooves.

In one embodiment of the invention, the recording and reproducingapparatus further includes a recording condition identifying portion forreading a recording condition identifier, provided in a particular zoneother than the information zone on the recording medium, for correctinga difference between characteristics of the concave portions and thoseof the convex portions of the guide grooves, wherein the wave formsetting portion is operated depending on information read by therecording condition identifying portion.

According to still another aspect of the invention, an opticalinformation recording and reproducing apparatus includes: a selectionportion for selecting which of the concave portions and the convexportions of the guide grooves are used for recording the informationsignal thereon or reproducing a recorded information signal therefrom;an optical portion, having a light source, for focusing a light beamemitted from the light source on the recording medium using an objectivelens; a focusing control portion, including an offset setting portionfor supplying offsets having at least two levels to the concave portionsand the convex portions of the guide grooves, for controlling so as tomake a focal point of the light beam correspond to a position of therecording thin film by using the offsets selected depending on a resultselected by the selection portion; a tracking control portion forcontrolling the position of the light beam in a direction substantiallyvertical to the guide grooves so that the light beam tracks the guidegrooves; and a polarity inverting portion for inverting the polarity ofan output signal from the tracking control portion depending on theresult selected by the selection portion.

In one embodiment of the invention, the recording and reproducingapparatus further includes a signal reproduction portion fordemodulating an information signal from a light reflected or transmittedby recorded marks recorded on the recording medium, wherein the focusingcontrol portion includes a focusing condition setting portion in which aplurality of offset levels for recording and reproducing the informationsignal are stored, and wherein before recording and reproducing theinformation signal on/from the recording medium, a plurality of recordedmarks are formed in a test zone close to an information zone on therecording medium by irradiating the light beam onto the concave portionsand/or the convex portions of the guide grooves using the plurality ofoffset levels, a plurality of reproduced signals to be obtained from theplurality of recorded marks formed on the recording medium aredemodulated by the signal reproduction portion using the light beam, andqualities of the plurality of reproduced signals obtained by the signalreproduction portion are compared with each other, thereby determiningrecording conditions optimized for the concave portions and the convexportions of the guide grooves.

In one embodiment of the invention, the recording and reproducingapparatus further includes a signal reproduction portion fordemodulating an information signal from a light reflected or transmittedby recorded marks on the recording medium, wherein the focusing controlportion includes a focusing condition setting portion in which aplurality of offset levels for recording and reproducing the informationsignal are stored, and wherein before recording or reproducing theinformation signal on/from the recording medium, information signals tobe obtained from reference recorded marks formed in a test zone close toan information zone on the recording medium are demodulated by thesignal reproduction portion using the light beam with the plurality ofoffset levels, and qualities of a plurality of reproduced signalsobtained by the signal reproduction portion are compared with eachother, thereby determining reproducing conditions optimized for theconcave portions and the convex portions of the guide grooves.

In one embodiment of the invention, the recording and reproducingapparatus further includes a jumping portion for moving the light beamby a half track from a concave portion of the recording medium to aconvex portion adjacent to the concave portion, or from a convex portionto a concave portion in association with an operation of the polarityinverting portion, wherein an offset at a level between a level of anoffset of the focusing control portion with respect to the concaveportions of the recording medium and a level of an offset of thefocusing control portion with respect to the convex portions of therecording medium is used during an operation of the jumping portion.

In one embodiment of the invention, the tracking control portioncomprises a second offset setting portion for supplying at least twooffset levels, and wherein the offset levels of the second offsetsetting portion are switched depending on a result selected by theselection portion.

According to still another aspect of the invention, an opticalinformation recording and reproducing apparatus includes: an opticalportion, having a light source, for focusing a light beam emitted fromthe light source on the recording medium using an objective lens; afocusing control portion for controlling so as to make a focal point ofthe light beam correspond to a position of the recording thin film; atracking control portion for controlling a position of the light beam ina direction substantially vertical to the guide grooves so that thelight beam tracks the guide grooves; a selection portion for selectingwhich of the concave portions and the convex portions of the guidegrooves are used for recording the information signal thereon orreproducing a recorded information signal therefrom; a polarityinverting portion for inverting the polarity of an output signal fromthe tracking control portion depending on the result selected by theselection portion; and a signal reproduction portion for demodulatingthe information signal from a light reflected or transmitted by recordedmarks recorded on the recording medium in the concave portions and theconvex portions of the guide grooves by switching at least twodemodulation conditions depending on the result selected by theselection portion.

In one embodiment of the invention, the mentioned at least twodemodulation conditions are equalizing conditions having differentamplification characteristics with respect to a frequency.

In one embodiment of the invention, the signal reproduction portionincludes at least two level setters for generating reference signals atdifferent levels and a comparator for comparing the information signalfrom the recording medium with one of the reference signals, and whereinthe said at least two demodulation conditions are the reference signalsfor binary coding.

In one embodiment of the invention, before demodulating the informationsignal from the recording medium, signals to be obtained from referencerecorded marks formed in the concave portions and the convex portions ofthe guide grooves in a test zone close to an information zone on therecording medium are reproduced; the signals are demodulated bygradually varying demodulation conditions of the signal reproductionportion; and then the demodulated signals are compared with each other,thereby determining optimal demodulation conditions.

According to still another aspect of the invention, an opticalinformation recording medium includes: a substrate having guide groovesconsisting of concave portions and convex portions thereon; a recordingthin film, provided on the substrate, on which variations to be detectedoptically are generated by irradiation of light; and land/grooveidentifiers, provided in a particular zone other than an informationzone on the recording thin film, for indicating differences betweencharacteristics of the concave portions and those of the convex portionsof the guide grooves.

In one embodiment of the invention, the land/groove identifiers includeinformation indicating irradiation conditions of light during arecording operation.

In one embodiment of the invention, the land/groove identifiers includeidentifiers consisting of information about groove shapes of the concaveportions and the convex portions of the guide grooves.

In one embodiment of the invention, the land/groove identifiers arereference record signals, provided on the concave portions and theconvex portions of the guide grooves in a test zone close to aninformation zone on the same plane of the recording medium, fordetermining reproduction conditions of the information signal recordedin the information zone.

According to the present invention, the recording conditions are varieddepending on which of the concave portions and the convex portions ofthe guide grooves are tracked, so that a recording may be performedwhile compensating for the difference between the heating/coolingcharacteristics of the grooves and those of the lands, wherebyinformation may be recorded stably.

In addition, any focusing errors and tracking errors which are causedduring tracking the concave portions and convex portions of the guidegrooves and the distortion of the reproduced signal to be generatedduring the signal demodulation may be compensated for independently.

Thus, the invention described herein makes possible the advantage ofproviding an optical information recording medium and an opticalinformation recording and reproducing apparatus in which reading errorsmay be reduced both on the lands and the grooves of the guide grooves.

This and other advantages of the present invention will become apparentto those skilled in the art upon reading and understanding the followingdetailed description with reference to the accompanying figures.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing the construction of an opticalinformation recording and reproduction apparatus according to thepresent invention.

FIG. 2 is a partial perspective view of an optical information recordingmedium of the present invention.

FIG. 3 is a block diagram showing the construction of a waveform settingportion according to a first example of the invention.

FIGS. 4A and 4B show the waveforms of the respective signals output frompattern setters according to the first example of the invention.

FIG. 5 shows the waveforms of the respective signals output fromwaveform setting portion and a recording state corresponding to thewaveforms of the respective signals output from the waveform settingportion according to the first example of the invention.

FIG. 6 is a perspective view showing a configuration for an opticalinformation recording medium according to the first example of theinvention.

FIG. 7 shows the waveforms of the respective signals output from arecording condition setter according to the first example of theinvention.

FIG. 8 is a flow chart showing the process in setting a recordingcondition according to the first example of the invention.

FIG. 9 is a block diagram showing the construction of a focusing controlportion according to a second example of the invention.

FIG. 10 is a block diagram showing the construction of a trackingcontrol portion according to the second example of the invention.

FIG. 11 is a flow chart showing the process in setting a servo conditionaccording to the second example of the invention.

FIG. 12 is a block diagram showing the construction of a binary codingportion according to a third example of the invention.

FIG. 13 is a flow chart showing the process in setting a reproductioncondition according to the third example of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, an example of an optical information recording medium andan optical information recording and reproducing apparatus according tothe present invention will be described with reference to theaccompanying drawings.

FIG. 1 is a block diagram showing the construction of an opticalinformation recording and reproduction apparatus according to thepresent invention. The optical information recording and reproducingapparatus of the invention includes: a spindle motor 2 for rotating anoptical disk 1, i.e., an optical information recording medium havingguide grooves consisting of convex portions and concave portions; anoptical pick-up 3 for focusing a light beam emitted from a light sourcesuch as a laser light source; and five circuit sections for controllingthe respective portions. The first section is an optical modulationsection 4 for driving the light source of the optical pick-up 3. Thesecond section is a control section 5 for focusing a light beam emittedfrom the pick-up 3 and for controlling the operation of the light beamsuch as a tracking operation on the guide grooves. The third section isa signal reproduction section 6 for reading an information signal formedon the optical disk. At least one of the three sections is provided withat least two kinds of condition setting functions in order to set theconditions optimized for lands and grooves of the guide grooves,respectively. The fourth section is a land/groove selection section 7(hereinafter, simply referred to as an “L/G selection section”) forswitching the conditions of the above three sections depending on theportion to be tracked by the light beam, i.e., which of the lands or thegrooves are to be tracked. The fifth section is a system control section8 for controlling the timings of the operations of the above fourcircuit sections. According to the present invention, in recordingand/or reproducing information on/from both of the lands and the grooveson an optical disk, by selecting an optimal condition for the circuitsections using the L/G selection section 7, the information may berecorded and reproduced with reduced errors.

As shown in FIG. 2, an optical disk 1 includes a substrate 25 havingguide grooves thereon consisting of concave portions and convexportions, and a recording thin film 26 causing the variations which canbe detected optically. As the recording thin film 26, a deformation typerecording thin film accompanying a change of the shape thereof owing tothe heat of the light beam; a phase-change type recording thin filmutilizing the change of the state in the phase of the thin film; amagnetooptic recording thin film utilizing the variation of themagnetization direction; and a recording thin film made of aphotochromic material, or the like in which the recording state changesby the use of the optical energy may be used. Furthermore, informationmay be reproduced from uneven pits provided in the vicinity of thecentral portions of the lands and grooves of the guide grooves. In sucha case, the medium may be used exclusively for reproducing theinformation, and the recording of the information thereon is impossible.

Again, referring to FIG. 1, in reproducing the information signalsrecorded on the optical disk, the spindle motor 2 is driven by arotation control portion 9 based on the instructions from the systemcontrol section 8 so as to rotate the optical disk 1 serving as therecording medium at a constant velocity. Next, control signalsindicating that the reproduction operation is being conducted are inputfrom the system control section 8 to a laser driving portion 10, therebycontrolling the amount of the, current flowing through the light source11 so that the intensity of the light beam emitted from the opticalpick-up 3 becomes constant. The light beam emitted from the light source11 is converged through the optical systems of the pick-up 3 and theultimate objective lens 12 so as to be irradiated on the optical disk 1.The light beam reflected by the optical disk 1 is passed through theobjective lens 12 and the optical systems in the pick-up 3 so as to beirradiated on a photodetector 13 having a number of dividedlight-receiving surfaces. The photodetector 13 photoelectricallyconverts the incident light beam, thereby outputting a signal having avoltage corresponding to the variation of the light amount received bythe respective light-receiving surfaces. The output signal from thephotodetector 13 is amplified by a preamp 14. The focal point of thelight beam is controlled by using low-frequency components in theamplified signal.

More specifically, a focusing control portion 16 obtains a focusingerror signal by using a part of the output signals from the respectivelight-receiving surfaces of the photodetector 13, and drives a voicecoil 15 of the optical pick-up 3 based on the signals, thereby slightlymoving the objective lens 12 in the direction vertical to the surface ofthe optical disk 1, so that the light spot is controlled so as to befocused on the recording thin film of the optical disk 1. On the otherhand, the tracking control portion 17 obtains a tracking control signalfrom the combination of other output signals from the photodetector 13so that the light beam tracks the guide grooves, and controls the voicecoil 15 to move slightly in a radial direction of the optical disk 1.

Then, the polarity of the output from the tracking control portion 17 isinverted by a polarity inverter 18 depending on which of the lands andthe grooves are tracked by the light beam. The inversion operation isconducted by the polarity inverter 18 by giving the instructions to theL/G selection section 7 for selecting the conditions of the lands andgrooves as well as to the optical modulation section 4 and the signalreproduction section 6 based on the control signal of the system controlsection 8. Consequently, it becomes possible for the light beam to trackthe groove portions and the land portions of the guide grooves formed onthe optical disk 1.

The quality of a recording medium and the apparatus is fluctuated duringthe production thereof in the following points. For example, the shapesof the guide grooves may become ununiform; the distribution of theintensity of the light beam emitted from the recording and reproducingapparatus may be distorted; or the sensitivity of the photodetector andthe like may become inconstant. Accordingly, during the servo operation,an error voltage which is not caused by the recording medium isinadvertently generated in the focusing error signal or a tracking errorsignal to be generated depending on which of the lands and the grooveson the guide grooves are to be irradiated with the light beam. In orderto correct these errors of the control signal, offset adjustment isperformed with respect to the respective control portions in associationwith the setting of the L/G selection section 7. For example, byapplying a slight amount of offset to the focusing control signal, thefocusing error to be generated between the lands and the grooves iscorrected, and in the same way, by applying an offset to the trackingcontrol signal, the tracking error is corrected. An optimal focusingstate may be obtained both on the lands and the grooves by employing theabove-described construction.

In the case where the light beam is moved to the adjacent track duringthe tracking operation, a jumping circuit 19 overlaps a pulse voltagefor instantaneously moving the voice coil 15 in a radial direction onthe output signal of the polarity inverter 18. Hereinafter, it will beassumed that a movement from a groove to an adjacent groove and amovement from a land to an adjacent land are defined as one track jump,and that a movement from a groove to an adjacent land and a movementfrom a land to an adjacent groove are defined as a half track jump. Itis noted that the polarity of the tracking is required to be inverted bythe polarity inverter 18 at the same time as the application of thejumping pulse during performing a half track jump. The jumping circuit19 makes it possible for the light beam to track an arbitrary portiondesignated by the system control section 8.

A binary coding portion 20 of the signal reproduction section 6 convertsa signal output from the preamp 14 into a binary-coded signal bycomparing the level of the signal with a reference level usinghigh-frequency components of the signal output from the preamp 14. Then,a decoder 21 demodulates the binary-coded signal in accordance with apredetermined signal format. As a result, an information signal from arecorded mark formed on the optical disk 1 is demodulated so as to betransmitted to an external apparatus as a data signal following theinstructions of the system control section 8. Also, if necessary, therecording and reproduction information on the lands and the groovesformed in particular regions on the optical disk 1 is demodulated by anL/G condition identifying portion 22. The information to be recognizedby the L/G condition identifying portion 22 is preferably recordedbeforehand during the process for producing the recording medium. Suchinformation includes information for correcting the difference betweenthe characteristics of the lands and those of the grooves, informationabout optimal conditions of the light irradiation for both of the landsand the grooves; information about optimal conditions of the focusingand tracking control; and information about optimal conditions of thedemodulation of the reproduced signal. Alternatively, the informationmay be about the shape of the guide grooves, e.g., the width of agroove, the depth of a groove, the pitch, and the properties on thesurface. In such a case, after identifying this value, optimalconditions for recording, servo and reproduction may be obtained basedon the correlation predetermined by the information about the shape.

Next, the recording of a signal on a recording medium will be described.First, a difference between a land and a groove during recording will beexplained. In almost all kinds of recording media which have been citedherein as optical type recording media, the temperature in a recordingthin film increases by absorbing the irradiated light, so that arecorded mark is formed on the thin film in accordance with thevariation of the temperature. Therefore, even if the energy of the lightfor recording is constant, the shape of the recorded mark becomesdifferent depending on the degree of the dissipation of heat in therecording thin film. More specifically, it is considered that theincrease in the temperature, the cooling condition after the increase inthe temperature, or the like becomes different because of the variousdifferences occurring during the process for forming the guide grooves:that is to say, the difference in the surface state such as thedifference between the roughness of a land and that of a groove; thedifference in the shapes of the edges of the guide grooves dividing theland and the groove; or the difference between the shape of the guidegrooves and that of the recording thin film.

In order to deal with the differences mentioned above, in the case ofrecording a signal on a recording medium, first, a record signal S01including the information to be recorded at predetermined timings isinput to the optical modulation section 4 by the system control section8. In the optical modulation section 4, the record signal S01 is firstconverted into a record signal in a predetermined format by the encoder23. Then, the division of pulses or the variation of the intensity isset with respect to the converted signal in accordance with theconditions determined by the waveform setting portion 24. Next, thelight intensity of the light source 11 is modulated by the laser drivingportion 10. The intensity-modulated light is absorbed by the recordingthin film on the optical disk 1, whereby a recorded mark is formed andthe signal recording is performed. The waveform setting portion 24 hasthe recording patterns optimized for recording a signal on a land and agroove, and the portion 24 is synchronized with the output of the L/Gselection section 7 so as to vary the output thereof. As a result, thelight intensity of the light source 11 may be modulated by the laserdriving portion 10 based on the modulated waveforms corresponding to aland and a groove, respectively.

By using the construction described above, it is possible to record asignal on a recording thin film on the conditions optimized for both ofthe land and the groove, or to reproduce the information signal recordedin such a way. Hereinafter, exemplary embodiments illustrating specificoperations will be described in detail below.

EXAMPLE 1

In this example, a method for setting respectively independent recordingconditions for a land and a groove during the recording of aninformation signal on an optical information recording medium will bedescribed. By switching the modulating waveform of the light duringrecording depending on which of the two portions, i.e., a land portionand a groove portion, is a signal recording face, the difference betweenthe thermal conditions on a land and those on a groove is compensated,thereby obtaining less distorted recorded marks on both of the portions.FIG. 3 shows the construction of the waveform setting portion 24 in theoptical modulation section 4. FIGS. 4A and 4B show the patterns set bythe waveform setting portion 24. FIG. 4A shows the patterns to be usedin recording a signal on a land, while FIG. 4B shows the patterns to beused in recording a signal on a groove. FIG. 5 is charts showing therelationship between the light output from the optical pick-up 3 basedon the signal input to the optical modulation section 4 and the signaloutput from the optical modulation section 4 and the timings of therecorded marks to be recorded on the optical information recordingmedium.

As shown in FIG. 3, the waveform setting portion 24 described referringto FIG. 1 includes: pattern setters 31 and 32 having in the memoriesthereof the reference pulse patterns 31 s and 32 s to be applied to aland and a groove, respectively; a pattern selector 33 for selectingeither one of the two patterns; and a pulse modulator 34 for convertinga coded signal into a pulse pattern. Since the L/G selection sectionoperates depending on which of the two portions is a signal recordingportion, based on the output signal 7 s from the L/G selection section,the pattern selector 33 selects either the pulse pattern of the outputsignal 31 s from the pattern setter 31 or that of the output signal 32 sfrom the pattern setter 32. The pulse modulator 34 outputs a modulatedpulse 34s corresponding to the inversion intervals of the coded signal23 s output from the encoder 23, based on the output pattern from thepattern selector 33. The pulse modulator 34 outputs to the laser drivingportion 10 a waveform varying among the three voltage levels Vp, Vb andVr corresponding to the respective irradiation powers Pp, Pb and Pr ofthe light beam focused on the optical information recording medium. Thelaser driving portion 10 converts a voltage of the output signal 34 sfrom the pulse modulator 34, into a current, thereby modulating thelight source 11. As a result, the optical pick-up 3 emits a light beamhaving a predetermined output waveform 11 s, so that predeterminedinformation is recorded on the optical information recording medium 1.

In FIGS. 4A, 4B, and 5, the parameters included in the pulse patternswhich the pulse modulator 34 receives are indicated only by thedispositions of the pulses and the widths of the pulses. However, theparameters may be effectively indicated by varying the intervals betweenthe pulses and the heights (irradiation powers) of the pulses.Particularly, in the case where the shapes of the recorded marks formedon the land and the groove on the recording medium are equivalent, butthe areas thereof are different from each other, or in the case ofemploying a modulation method which is not so affected by the differencein the shapes of the recorded marks, it is sufficient to set theirradiation powers at the values corresponding to a land and a groove,respectively. In such a case, the structure of the setting circuit maybe considerably simplified.

The pulse patterns to be set by the pattern setters 31 and 32 as shownin FIGS. 4A and 4B correspond to the case where the pulses areintensity-modulated based on the level of the output 23 s from theencoder 23, i.e., a mark length recording. The pulse patterns may alsocorrespond to the case where the pulses are generated every time thelevel of the output 23 s from the encoder 23 is inverted, i.e., a markposition recording.

In the case corresponding to the mark length recording, a multiple pulsemodulation method for forming a plurality of pulse sequences withrespect to the inversion of a single signal as shown in FIG. 5 isemployed. This method is utilized for preventing the distortion of therecorded mark because of the heat transfer when an optical informationrecording medium is irradiated with the light. More specifically, theenergy density in the portion where the signal is inverted, i.e., thestarting point of the recording, is set to be high, while the energydensity thereafter is set to be low, whereby a symmetrically recordedmark may be recorded. As a result, the temperature of the recording thinfilm becomes substantially constant between the starting point and theterminal point of the recording, thereby obtaining a symmetricallyrecorded mark. However, in a land and a groove, even if the irradiationconditions of the light are the same, the heating/cooling conditions ofthe recording film are different from each other, as described above.Thus, according to the present invention, the pulse patterns are set soas to optimize the irradiation conditions of the light for the twoportions. For example, in the case where the encoder 23 corresponds toan EFM (eight to fourteen modulation) converting used for a compactdisk, etc., the number of the inversion intervals of the signal 23 sbecomes nine, i.e., from 3 T to 11 T, where T is a period of clock. Inthis case, as shown in FIGS. 4A and 4B, the nine kinds of set patternsto be recorded on a land and a groove are stored in the pattern setters31 and 32, respectively. Then, the nine kinds of patterns read from thepattern setters 31 and 32 are output from the pattern selector 33; andthe patterns are input to the pulse modulator 34, where a pattern havinga cycle corresponding to the inversion interval of the output 23 s fromthe encoder 23 is selected.

On the other hand, in the case of the mark position recording, theshapes of the recorded marks to be formed on the two portions on theoptical information recording medium are the same, and the intervalthereof becomes an information signal, so that it is sufficient for thepattern setters 31 and 32 to set only one kind of pulse patternconsisting of a pulse width and a power value for the land and thegroove, respectively. Accordingly, the structure of the pattern settermay be simplified as compared with the case of the mark lengthrecording.

In the method described above, the pulse patterns corresponding to aland and a groove are stored beforehand inside the memories of thepattern setters 31 and 32. On the other hand, in the case wheredifferent pulse patterns are employed for different kinds of recordingmedia, and in the case where a recording is intended to be performedwith an: even higher precision, the following two methods are employed.

According to a first method, a trial recording is performed beforerecording the information signal. Various differences between a land anda groove including the difference between optical information recordingmedia; the difference between recording and reproducing apparatuses; thevariation of the ambient temperature around the recording andreproducing apparatus; the adhesion of dust to a recording medium or anoptical system, and the like are corrected. In this case, every time avariation factor varying the recording conditions of a recording mediumis detected, a trial recording is performed so as to select an optimalpulse pattern, thereby resetting the pulse, pattern. FIG. 8 is a flowchart illustrating the trial recording process. FIG. 6 is a perspectiveview of an optical disk. FIG. 7 shows the various pulse patterns usedfor the trial recording process. Hereinafter, the trial recordingprocess will be described with reference to FIG. 6 through FIG. 8.

The trial recording process is begun by the input of a reference signalS03 indicating the generation of a variation factor in the opticalinformation recording medium to the system control section 8, as shownin FIG. 1. As shown in FIG. 8, the trial recording is begun by theinstruction 81 indicating the start of the trial recording from thesystem control section 8. As shown in FIG. 6, following the instruction82 indicating the movement of the light beam 27 to the test zone 62 onthe optical disk 1, the position of the light beam 27 used for recordingand reproduction is moved to the test zone 62 close to the informationzone 61 on the same plane of the optical disk 1. Next, following theinstruction 83 indicating the pattern setting, a first pulse pattern inthe recording condition setter 36 (shown in FIG. 3) in which a pluralityof pulse patterns are stored is read into the pattern setters 31 and 32.Next, in accordance with the recording pattern, the driver 10 isoperated (as shown in FIG. 1), and, following the instruction 84indicating the light irradiation, a modulated light is first irradiatedon a groove. Subsequently, in the same way, a series of lightirradiation steps are performed on a land. The recording conditionsetter 36 sets various pulse patterns in which the energy distributionat the starting point of the recording is different from that to beobtained after the point in order to obtain a symmetrically recordedmark with respect to various recording media and various environmentalconditions during the operation of the apparatus, as indicated by the 15exemplary pulse patterns of 11 T in FIG. 7. These pulse patterns (15pulse patterns in this example) are sequentially output depending on theresult determined by the identification test 85 of the next pulsepattern. As a result, the recorded marks in respectively differentshapes corresponding to the recording conditions are formed on therecording medium. Next, a signal is reproduced from the recorded markson the recording medium. During the reproduction of the signal, theerror rate of each signal reproduced from each recorded mark is detectedin the error detection step 86, and the detected values are comparedwith each other in the error rate comparison step 87, whereby an optimalrecording condition is obtained. The error rate is detected by using theerror correction signal generated during the demodulation of the data bythe decoder 20. The error rates are compared with each other by thesystem control section 8 so as to obtain a recording condition where theerror rate becomes minimal. As a result, an optimal pattern may beselected. By performing the trial recording process for each of the landand the groove, a pulse pattern optimized for each of the land and thegroove may be obtained.

In the case where the time required for this trial recording process isdesired to be shortened, or in the case where the construction of thecircuit is desired to be simplified, some of these steps may be omitted.For example, the correlation between a land and a groove is obtainedbeforehand, and the trial recording is performed only for the land,thereby obtaining a pulse pattern optimized for the land. Then, based onthe correlation mentioned above, a pulse pattern for a groove may beobtained.

The recording condition setter 36 should be operated based on thereference signal S03, for example, when the optical disk is exchanged;when the disk drive is actuated; when the temperature of the operatingenvironment has been varied by a predetermined amount or more; when apredetermined time period has passed after setting the recordingconditions; or when a predetermined amount or more of error has beendetected from a reproduced signal. When the disk is exchanged, or whenthe drive is actuated, the variation factors in each of the disk and thedrive, or those between the disk and the drive may be detected. Bymanaging the variation of the temperature of the operating environmentand the time period passed after setting the recording conditions, thedependence of the recording medium on the temperature, or the variationof the controlled state of the drive may be compensated.

According to a second method, a recording condition optimized for eachof a land and a groove, i.e., an identifier indicating an optimalrecording condition, is recorded in a predetermined region on theoptical information recording medium. An identifier includes informationof pulse patterns optimal for both of a land and a groove, and isprovided in a form based on that of an information signal or that of anaddress signal in an internal region or an external region other thanthe information zone of the optical disk. The identifier may beprovided, for example, in a region corresponding to the test zone 62adjacent to the information zone 61 on the same plane of the opticaldisk 1 as shown in FIG. 6. In such a case, the form of the identifiermay be the same as that of an information signal, however, in view ofthe improvement of the reading accuracy, the identifier is preferably acoded signal having a relatively low recording density as compared withthat of the information signal, and the identifier is preferablyprovided in either a land or a groove of the guide grooves. Theidentifier in such a form is processed in the signal reproductionsection 6 in the same way as the information signal, and the informationincluded in the identifier is demodulated by the L/G conditionidentifying portion 22 after the reproduced signal is binary-coded at apredetermined level. Based on the results, the system control section 8sets the recording conditions for the optical modulation section 4.

The identifier may be provided in various other forms in accordance withthe size of the apparatus to be used: for example, the identifier may beprovided in a part of a protection plate or a cartridge for protectingthe medium; the identifier may be provided by printing information; aparticular shape may be used for the identifier; or a semiconductormemory may be provided for functioning as the identifier. When theinformation from these identifiers is supplied to a recording andreproducing apparatus through an optical information recording medium,the information is read out by the system control section 8, so that thepatterns to be output from the pattern setters 31 and 32 are set basedon the contents of the information. By using the above-mentionedconstruction, the irradiation conditions of the light may be set so asto be optimized for the kind of the recording medium to be used.

According to the construction described above, every time a referencesignal for setting the recording conditions of an optical disk isoutput, the recording conditions are reset, so that the recording of thedata may always be performed in an optimal state, and the reliability asa data recording apparatus may be improved.

EXAMPLE 2

In this example, a method for enabling the focusing to be optimized forboth a land and a groove and optimal tracking of the guide grooves byswitching the servo conditions for a land and a groove when a light beamis irradiated on an optical information recording medium.

As focusing techniques for focusing a light beam on an opticalinformation recording medium, a knife edge method, an astigmatism methodand the like are known. According to the knife edge method, thedetection system to be used becomes disadvantageously large because theoptical members are required to be positioned with high precision. Onthe other hand, according to the astigmatism method, it is easy todownsize a detection system. According to the astigmatism method,however, in performing a precise focusing control for both of a land anda groove, which is the main objective of the present invention, adifference is not supposed to be generated between a land and a groovein an ideal state. But, in actuality, if slight distortion is present inthe shape of the guide grooves or in the shape of a beam spot, thedistribution of the light beam reflected by the recording medium isaffected by the distortion, so that the patterns on the photodetector 13become different. According to the method of the present invention, thedifference in the shapes of the beam spots on the photodetector 13 foreach of a land and a groove is compensated by applying an offset to afocusing control signal.

FIG. 9 shows the detail of a focusing control portion 16. A focusingerror signal 90 s is obtained by the focusing error detector 90 based onthe signal components of the output signal 14 s from the preamp whichrelate to the focusing control. The focusing error signal 90 s is inputthrough a focusing compensator 91 to a focusing driver 92, therebyobtaining a focusing control signal 16 s. Then, by driving the voicecoil 15 of the optical pick-up 3 based on the focusing control signal 16s, the focusing control may be performed.

The focusing compensator 91 is constructed so as to set a plurality ofoffset levels in response to the signals externally applied. The offsetsto be input to the focusing compensator 91 are generated in an offsetsetter 93 for setting an offset when a land is tracked; an offset setter94 for setting an offset when a groove is tracked; and an offset setter95 for setting an offset when a half track jump operation is performedfrom a land to a groove, or from a groove to a land. The offset selector96 outputs either a signal from the offset setter 93 or a signal fromthe offset setter 94 in response to the output 7 s from the L/Gselection section 7. In the case where the instruction indicating a halftrack jump is input to the offset selector 96 from the system controlsection, the level of the output from the offset selector 96 becomesequal to the level of the output from the offset setter 95.

The setting of the offset of the half track jump is performed forstabilizing the operation before and after the track jump when thedifference between the levels of the offset setter 93 and those of theoffset setter 94 is considerably large. On the other hand, in the casewhere the difference in the levels is small, the offset settingoperation may be omitted. The focusing driver 92 outputs a signal foroffsetting the input signal 91 s thereto so as to reduce the level ofthe signal 91 s to zero, thereby driving the voice coil 51. The gainused for this focusing driver 92 is generated in a gain setter 97 forsetting a gain when a land is tracked, and in a gain setter 98 forsetting a gain when a groove is tracked. A gain selector 99 outputseither a signal from the gain setter 97 or a signal from the gain setter98 in response to the output 7 s from the L/G selection section 7. Byusing the above-mentioned construction, a focusing state optimized forboth a land and a groove may be set.

In controlling the tracking, it becomes possible to record and reproducemore satisfactorily if setting a state optimized for both of a land anda groove. FIG. 10 shows the detail of the tracking control portion 17. Atracking error signal 100 s is output from a tracking error detector 100based on the signal components of the output signal 14 s from the preampwhich relate to the tracking control. The tracking error signal 100 s isinput through a tracking compensator 101 to a tracking driver 102 so asto output a tracking control signal 17 s. The tracking error signal 17 sis input to a polarity inverter 18 so as to drive the voice coil 15 ofthe optical pick-up 3, thereby controlling the tracking.

The tracking compensator 101 is constructed so as to set a plurality ofoffset levels in response to a signal externally applied. The offsets tobe input to the tracking compensator 101 are generated in an offsetsetter 103 for setting an offset when a land is tracked; an offsetsetter 104 for setting an offset when a groove is tracked; and an offsetsetter 105 for setting an offset when a half track jump operation isperformed from a land to a groove, or from a groove to a land. Theoffset selector 106 outputs either a signal from the offset setter 103or a signal from the offset setter 104 in response to the output 7 sfrom the L/G selection section 7. In the case where the instructionindicating a half track jump is input to the offset selector 106 fromthe system control section, the level of the output from the offsetselector 106 becomes equal to the level of the output from the offsetsetter 105.

The setting of the offset during the performance a half track jump isemployed for stabilizing the operation before and after the track jumpwhen the difference between the levels of the offset setter 103 andthose of the offset setter 104 is considerably large. On the other hand,in the case where the difference in the levels is small, the offsetsetting operation may be omitted.

The tracking driver 102 outputs a signal for offsetting the input signal101 s thereto so as to reduce the level of the signal 101 s to zero,thereby driving the voice coil 15. A gain used for this tracking driver102 is generated in a gain setter 107 for setting a gain when a land istracked, and in a gain setter 108 for setting a gain when a groove istracked. A gain selector 109 outputs either a signal from the gainsetter 107 or the signal from the gain setter 108 in response to theoutput 7 s from the L/G selection section 7. By using theabove-mentioned construction, a tracking state optimized for both a landand a groove may be set.

Also, in order to set an optimal focusing condition or an optimaltracking condition, the recording and reproduction operation may beperformed while varying gradually the servo conditions before recordingand reproducing a signal in the same way as the trial-write operation asdescribed in Example 1. This process may be performed in almost the sameprocedures as those of the trial-write process as described withreference to FIG. 8.

In setting a focusing condition, as shown in FIG. 9, a system controlsignal 8 s is input via a focusing condition setter 141 to the offsetsetters 93, 94 and 95 and the gain setters 97 and 98. As shown in FIG.11, following the instruction 111 indicating the start of the testreproduction, the light beam is moved to the test zone on the opticaldisk as indicated by 112, so that the reproduction of the signal isbegun by scanning a track on which reference recording marks have beenrecorded beforehand. Next, in the servo condition setting step 113, afocusing offset and a focusing gain are selected based on the signaloutput from the focusing condition setter 141. Then, in the error ratedetection step 114, the signal is demodulated so as to estimate theerror rate. Next, in the servo condition identification step 115, thenext servo condition for the servo condition setter 141 is identified.If there remains any set conditions which are yet to be executed, thenthe servo condition setting step 113 is repeatedly performed, therebyexecuting all the set conditions. The obtained results are compared witheach other in the error rate comparison step 116, thereby determining anoptimal focusing condition.

In setting a tracking condition, as shown in FIG. 10, a system controlsignal 8 s is input via the tracking condition setter 142 to the offsetsetters 103, 104 and 105 and the gain setters 107 and 108. An optimaltracking condition is determined in the procedures shown in FIG. 13.

In this example, a method for reproducing reference recording marksrecorded beforehand in the test zone has been described. The servoconditions during recording may be obtained by performing a trialrecording process in the test zone where these servo conditions aremodified and by demodulating the reproduced signals from the respectivetrial recorded marks. In such a case, it is sufficient to additionallyperform a light irradiation step for recording between the servocondition setting step 113 and the error rate detection step 114. Thereoften exists a slight difference between an optimal servo condition thusobtained during recording and an optimal condition during reproduction.In order to eliminate the effect of such a difference, depending onnecessity, either of the two values is adopted or the servo conditionsare switched in the recording and in the reproduction. By using theabove-described construction, it becomes possible to record on the landand the groove so as to correspond to the variation between the disks orthe variation of the recording and reproducing apparatus.

EXAMPLE 3

In this example, a method for switching demodulation conditions for aland and a groove when an information signal is demodulated based on thereflected light from the light beam irradiated on the opticalinformation recording medium by omitting or simplifying a step in whichthe recording conditions are switched for a land and a groove duringrecording. The objective of the method of this example is to correct thedifference in the signal amplitude and the difference in the mark lengthdependence of the signal amplitude among various differences between thereproduced signal of a land and that of a groove. It is noted that themark length difference refers to an amplitude dependence between ashortest recorded mark and a longest recorded mark among the recordedmarks to be formed in response to the information signal.

FIG. 12 shows the detail of the binary coding portion 20. A high-passfilter (HPF) 120 outputs high-frequency components of the output signal14 s from the preamp. The high frequency components of the signal bandsof the signal output from the HPF 120 are further amplified by theequalizer 121 so as to be output as the signal 121 s. The signal 121 sis transmitted through a comparator 122 and a phase compensator 129 soas to be input to a decoder 21 as a binary-coded signal 20 s, so thatthe information signal is demodulated. The binary-coded signal 20 s isalso input to the L/G condition identifying portion 22, therebymonitoring the reproduction state.

The equalizer 121 is constructed so as to arbitrarily set the frequencyband of the equalizing and the equalizing characteristics such as a gainin response to the signal externally applied. The equalizer 121 isconnected via a gain selector 125 to a gain setter 123 for setting again when a land is tracked, and a gain setter 124 for setting a gainwhen a groove is tracked. The gain selector 125 outputs one of thevalues set by the gain setters 123 and 124.to the equalizer 121 based onthe output 7 s from the L/G selection section 7. The equalizer 121equalizes the signal passed through the HPF 120 based on the set gainreceived from the gain selector 125 thereby outputting the signal as thesignal 121s.

The comparator 122 compares the level of the signal 121 s with areference level, thereby outputting the obtained binary coded signal tothe phase compensator 129. The phase compensator 129 compensates thephase of the binary coded signal, thereby outputting the signal as thephase-compensated binary-coded signal 20 s. The slice level to be usedas a reference level for the comparator 122 is set in the level setter126 for setting a level when a land is tracked and in the level setter127 for setting a level when a groove is tracked.

The level selector 128 outputs either one of the values set by the levelsetters 126 and 127 to the comparator 122 based on the output 7 s fromthe L/G selection section 7, thereby supplying a reference level to thecomparator 122. By using the above-described construction, thereproduced signal is binary-coded at an optimal slice level for both aland and groove. By processing the information signal recorded on theland and the groove in the respectively independent conditions, itbecomes possible to reduce the difference between the recordingcharacteristics on a land and those on a groove.

Also, it is effective to provide a reproduction condition setting stepfor setting reproduction conditions beforehand in the same way as thetrial recording process as described in Example 1 as a method forsetting an optimal equalizing condition or an optimal slice condition.In performing this step, the procedures based on those of thetrial-write process as described with reference to FIG. 8 may be used.In the case of setting the reproduction conditions, as shown in FIG. 12,the system control signal 8 s is input via the reproduction conditionsetter 143 to the gain setters 123 and 124 and the level setters 126 and127.

As shown in FIG. 13, following the instruction 131 indicating the startof the test reproduction, the light beam is moved to the test zone onthe optical disk, so as to start the reproduction of the signal byscanning the track on which reference recording marks have been recordedbeforehand. Subsequently, in the reproduction condition setting step133, an equalizing characteristic and a slice level are set based on thesignal output from the reproduction condition setter 143. Then, thesignal is demodulated in the error rate detection step 134 so as toevaluate the error rate. The next reproduction condition for thereproduction condition setter 143 is identified in the reproductioncondition identification step 135. If there remains any reproductioncondition which are yet to be performed, then the reproduction conditionsetting step 133 is repeatedly performed, thereby performing all the setconditions. The obtained results are compared in the error ratecomparison step 136, thereby determining an optimal reproductioncondition.

By using the above-mentioned construction, it becomes possible toreproduce the signals recorded on a land and a groove in response to thevariation between the respective disks or the variation of the recordingand reproducing apparatus. In addition, by additionally providing arecording condition setting step as described in Examples 1 and 2 beforethe reproduction condition setting step, the quality of the recordingand reproducing apparatus may be further improved.

In Examples 1 through 3, the recording medium has not been described indetail. However, the present invention is applicable to all kinds ofrecording media which exhibit recording conditions to be detectedoptically. The depth of the groove serving as a parameter of the shapeof a groove, and the angle of the inclined regions in the bordersbetween lands and grooves have not been described in detail. However,these are not restrictions of the present invention, either.

The present invention has been described with respect to the opticalmodulation section in Example 1; the control section in Example 2; and amethod for compensating the differences between the characteristics of aland and those of a groove without any relation to the signalreproduction section. It is clear that the above-mentioned conditionsmay be used in free combinations thereof or in simplified forms inaccordance with the characteristics of the recording medium and thenecessary level of the signal to be output from the recording andreproducing apparatus.

Various other modifications will be apparent to and can be readily madeby those skilled in the art without departing from the scope and spiritof this invention. Accordingly, it is not intended that the scope of theclaims appended hereto be limited to the description as set forthherein, but rather that the claims be broadly construed.

1. An optical information recording and reproducing apparatus forrecording and reproducing an information signal on/from both concaveportions and convex portions of guide grooves formed on a recordingmedium, the recording medium having: a substrate on which the guidegrooves consisting of the concave portions and the convex portions areformed; and a recording thin film, formed on the guide grooves, on whichvariations to be detected optically are generated by irradiation oflight, the optical information recording and reproducing apparatuscomprising: an optical means, having a light source, for focusing alight beam emitted from the light source on the recording medium usingan objective lens; a focusing control means for controlling so as tomake a focal point of the light beam correspond to a position of therecording thin film; a tracking control means for controlling a positionof the light beam in a direction substantially vertical to the guidegrooves so that the light beam tracks the guide grooves; a selectionmeans for selecting which of the concave portions and the convexportions of the guide grooves are used for recording the informationsignal thereon or reproducing a recorded information signal therefrom; apolarity inverting means for inverting a polarity of an output signalfrom the tracking control means depending on a result selected by theselection means; a waveform setting means for setting a modulationpattern for the light beam to be irradiated on the recording medium inaccordance with the information signal; and a signal reproduction meansfor demodulating the information signal from a light reflected ortransmitted by recorded marks recorded on the recording medium; whereinat least one of the focusing control means, the tracking control means,the waveform setting means and the signal reproduction means has atleast two kinds of operating conditions for recording and reproducingthe information signal on/from the concave-portions and the convexportions of the guide grooves, and wherein the operating conditions areselected depending on the result selected by the selection means.
 2. Anoptical information recording and reproducing apparatus for recordingand reproducing an information signal on/from both concave portions andconvex portions of guide grooves formed on a recording medium, therecording medium having: a substrate on which the guide groovesconsisting of the concave portions and the convex portions are formed;and a recording thin film, formed on the guide grooves, on whichvariations to be detected optically are generated by irradiation oflight, the optical information recording and reproducing apparatuscomprising: an optical means, having a light source, for focusing alight beam emitted from the light source on the recording medium usingan objective lens; a focusing control means for controlling so as tomake a focal point of the light beam correspond to a position of therecording thin film; a tracking control means for controlling a positionof the light beam in a direction substantially vertical to the guidegrooves so that the light beam tracks the guide grooves; a selectionmeans for selecting which of the concave portions and the convexportions of the guide grooves are used for recording a informationsignal thereon or reproducing a recorded information signal therefrom; apolarity inverting means for inverting a polarity of an output signalfrom the tracking control means depending on a result selected by theselection means; and an optical modulation means including a waveformsetting means having at least two kinds of modulation patterns inaccordance with the information signal in order to record theinformation signal on each of the concave portions and the convexportions of the guide grooves so as to output any of the modulationpatterns depending on the result selected by the selection means,wherein the optical modulation means modulates an intensity of the lightbeam in accordance with the modulation patterns output from the waveformsetting means.
 3. A recording and reproducing apparatus according toclaim 2, wherein the waveform setting means has a multiple pulsemodulation function for irradiating a light consisting of a plurality ofpulse sequences onto one recorded mark to be recorded on the recordingmedium, and wherein waveforms of the plurality of pulse sequences aredifferent from each other among the at least two kinds of modulationpatterns of the waveform setting means.
 4. A recording and reproducingapparatus according to claim 2, wherein the at least two kinds ofmodulation patterns of the waveform setting means vary a power of thelight beam.
 5. A recording and reproducing apparatus according to claim2 further comprising a signal reproduction means for demodulating theinformation signal from a light reflected or transmitted by recordedmarks recorded on the recording medium, wherein before recording theinformation signal on the recording medium, the waveform setting meansincludes a recording condition setting means in which a plurality ofpulse patterns are stored in order to irradiate the light beam havingdifferent modulation patterns onto the concave portions and/or theconvex portions of the guide grooves in a test zone close to aninformation zone on the recording medium and wherein a plurality ofrecorded marks are formed on the recording medium by irradiating thelight beam modulated by the optical modulation means in accordance withthe plurality of pulse patterns, information signals to be obtained fromthe plurality of recorded marks formed on the recording medium aredemodulated by the signal reproduction means, and qualities of aplurality of reproduced signals obtained by the signal reproductionmeans are compared with each other, thereby determining recordingconditions optimized for the concave portions and the convex portions ofthe guide grooves.
 6. A recording and reproducing apparatus according toclaim 2 further comprising a recording condition identifying means forreading a recording condition identifier, provided in a particular zoneother than the information zone on the recording medium, for correctinga difference between characteristics of the concave portions and thoseof the convex portions of the guide grooves, wherein the wave formsetting means is operated depending on information read by the recordingcondition identifying means.
 7. An optical information recording andreproducing apparatus for recording and reproducing an informationsignal on/from both concave portions and convex portions of guidegrooves formed on a recording medium, the recording medium having: asubstrate on which the guide grooves consisting of the concave portionsand the convex portions are formed; and a recording thin film, formed onthe guide grooves, on which variations to be detected optically aregenerated by irradiation of light, the optical information recording andreproducing apparatus comprising: a selection means for selecting whichof the concave portions and the convex portions of the guide grooves areused for recording the information signal thereon or reproducing arecorded information signal therefrom; an optical means, having a lightsource, for focusing a light beam emitted from the light source on therecording medium using an objective lens; a focusing control means,including an offset setting means for supplying offsets having at leasttwo levels to the concave portions and the convex portions of the guidegrooves, for controlling so as to make a focal point of the light beamcorrespond to a position of the recording thin film by using the offsetsselected depending on a result selected by the selection means; atracking control means for controlling a position of the light beam in adirection substantially vertical to the guide grooves so that the lightbeam tracks the guide grooves; and a polarity inverting means forinverting a polarity of an output signal from the tracking control meansdepending on the result selected by the selection means.
 8. A recordingand reproducing apparatus according to claim 7 further comprising asignal reproduction means for demodulating an information signal from alight reflected or transmitted by recorded marks recorded on therecording medium, wherein the focusing control means includes a focusingcondition setting means in which a plurality of offset levels forrecording and reproducing the information signal are stored, and whereinbefore recording and reproducing the information signal on/from therecording medium, a plurality of recorded marks are formed in a testzone close to an information zone on the recording medium by irradiatingthe light beam onto the concave portions and/or the convex portions ofthe guide grooves using the plurality of offset levels, a plurality ofreproduced reference signals to be obtained from the plurality ofrecorded marks formed on the recording medium are demodulated by thesignal reproduction means using the light beam, and qualities of theplurality of reproduced signals obtained by the signal reproductionmeans are compared with each other, thereby determining recordingconditions optimized for the concave portions and the convex portions ofthe guide grooves.
 9. A recording and reproducing apparatus according toclaim 7 further comprising a signal reproduction means for demodulatingan information signal from a light reflected or transmitted by recordedmarks on the recording medium, wherein the focusing control meansincludes a focusing condition setting means in which a plurality ofoffset levels for recording and reproducing the information signal arestored, and wherein before recording or reproducing the informationsignal on/from the recording medium, information signals to be obtainedfrom reference recorded marks formed in a test zone close to aninformation zone on the recording medium are demodulated by the signalreproduction means using the light beam with the plurality of offsetlevels, and qualities of a plurality of reproduced signals obtained bythe signal reproduction means are compared with each other, therebydetermining reproducing conditions optimized for the concave portionsand the convex portions of the guide grooves.
 10. A recording andreproducing apparatus according to claim 7 further comprising a jumpingmeans for moving a the light beam by a half track from a concave portionof the recording medium to a convex portion adjacent to the concaveportion, or from a convex portion to a concave portion in associationwith an operation of the polarity inverting means, wherein an offset ata level between a level of an offset of the focusing control means withrespect to the concave portions of the recording medium and a level ofan offset of the focusing control means with respect to the convexportions of the recording medium is used during an operation of thejumping means.
 11. A recording and reproducing apparatus according toclaim 7, wherein the tracking control means comprises a second offsetsetting means for supplying at least two offset levels, and wherein theoffset levels of the second offset setting means are switched dependingon a result selected by the selection means.
 12. An optical informationrecording and reproducing apparatus for recording and reproducing aninformation signal on/from both concave portions and convex portions ofguide grooves formed on a recording medium, the recording medium having:a substrate on which the guide grooves consisting of the concaveportions and the convex portions are formed; and a recording thin film,formed on the guide grooves, on which variations to be detectedoptically are generated by irradiation of light, the optical informationrecording and reproducing apparatus comprising: an optical means, havinga light source, for focusing a light beam emitted from the light sourceon the recording medium using an objective lens; a focusing controlmeans for controlling so as to make a focal point of the light beamcorrespond to a position of the recording thin film; a tracking controlmeans for controlling a position of the light beam in a directionsubstantially vertical to the guide grooves so that the light beamtracks the guide grooves; a selection means for selecting which of theconcave portions and the convex portions of the guide grooves are usedfor recording the information signal thereon or reproducing a recordedinformation signal therefrom; a polarity inverting means for inverting apolarity of an output signal from the tracking control means dependingon the result selected by the selection means; and a signal reproductionmeans for demodulating the information signal from a light reflected ortransmitted by recorded marks recorded on the recording medium in theconcave portions and the convex portions of the guide grooves byswitching at least two demodulation conditions depending on the resultselected by the selection means.
 13. A recording and reproducingapparatus according to claim 12, wherein the at least two demodulationconditions are equalizing conditions having different amplificationcharacteristics with respect to a frequency.
 14. A recording andreproducing apparatus according to claim 12, wherein the signalreproduction means includes at least two level setters for generatingreference signals at different levels and a comparator for comparing theinformation signal from the recording medium with one of the referencesignals, and wherein the at least two demodulation conditions arereference signals for binary coding.
 15. A recording and reproducingapparatus according to claim 12, wherein, before demodulating theinformation signal from the recording medium, signals to be obtainedfrom reference recorded marks formed in the concave portions and theconvex portions of the guide grooves in a test zone close to aninformation zone on the recording medium are reproduced; the signals aredemodulated by gradually varying demodulation conditions of the signalreproduction means; and then the demodulated signals are compared witheach other, thereby determining optimal demodulation conditions.
 16. Anoptical information recording medium comprising: a substrate havingguide grooves consisting of concave portions and convex portionsthereon; a recording thin film, provided on the substrate, on whichvariations to be detected optically are generated by irradiation oflight; and land/groove identifiers, provided in a particular zone otherthan an information zone on the recording thin film, for indicatingdifferences between characteristics of the concave portions and those ofthe convex portions of the guide grooves.
 17. A recording mediumaccording to claim 16, wherein the land/groove identifiers includeinformation indicating irradiation conditions of light during arecording operation.
 18. A recording medium according to claim 16,wherein the land/groove identifiers include identifiers consisting ofinformation about groove shapes of the concave portions and the convexportions of the guide grooves.
 19. A recording medium according to claim16, wherein the land/groove identifiers are reference record signals,provided on the concave portions and the convex portions of the guidegrooves in a test zone close to an information zone on a same plane ofthe recording medium, for determining reproduction conditions of theinformation signal recorded in the information zone.